1. Field of the Invention
This invention relates to microfibers-generating fibers and a woven or non-woven fabric of microfibers, obtained by using the microfibers-generating fibers. More particularly it relates to the production of microfibers-generating fibers according to a melt blown process, making it possible to generate microfibers finer than conventional microfibers, and a woven or non-woven fabric using the aforementioned microfibers.
2. Description of the Related Art
Recently, with the high quality and diversity of fiber products, improvement in the feeling of fiber products by the use of microfibers has been researched. Furthermore, with the development of the use applications thereof, demand for microfibers in the fields of synthetic fibers and non-woven fabrics have also been increasing.
As for the processes which produce microfibers, those which remove the sea part of island-in-sea type fibers and use the resulting island part of the fiber as microfibers have been disclosed. For example, Japanese patent publication No. Sho 47-37648 discloses a process of melt-spinning a blend of different kinds of polymers consisting of a polymer for the sea component and a polymer for the island component followed by the removal of the sea component with a solvent. Further, Japanese patent application laid-open No. Sho 60-21904 discloses a process of conjugate-spinning different kinds of polymers into island-in-sea fibers followed by the removal of the sea component. However, since polymers capable of being removed with solvents are generally inferior in their spinnability, it has been difficult to obtain island-in-sea type conjugate fibers having a fineness of a single fiber of 1 denier or less, and hence it has been also difficult to obtain microfibers having a single fiber of 0.01 denier or less from the conjugate fibers.
The process of adding a dispersant in order to disperse the island component finely in the sea component has been proposed. However, this process is undesirable because of the complicated operation involved. Furthermore, there is a problem in that fibers having a fineness of a single fiber of 1 denier or less are inferior in their processability during the post-processing treatment of making the fibers into a non-woven fabric, such as carding.